An International Workshop on Mechanisms of Cell-Mediated Cytotoxicity will be held September 14-17, 198l, in Carry-Le-Rouet, France, involving approximately 50 active participants. This site was chosen principally because it is centrally located for majority of participants who will be European (and from as far away as Israel), and because the Conference Center rates are quite reasonable (see Budget section). These active participants will represent the major experimental systems in which cell-mediated cytotoxicity is currently studied: cytotoxic T lymphocytes (CTL), directed against both allogeneic and syngeneic targets; natural killers (NK); antibody-dependent cell-mediated cytotoxicity (ADCC); lectin-dependent cell-mediated cytotoxicity; and direct macrophage mediated cytotoxicity. The major objective of this workshop will be to compare and integrate what is known about the mechanism(s) of cytotoxicity in each system; to determine whether, on the basis of information now at hand, it seems likely that the mechanisms of cytotoxicity in the various systems are the same or are unique; and to synthesize new approaches to elucidating the fundamental mechanism(s) of cell-mediated cytotoxicity. Specific efforts will be made not to allow the Workshop to be used simply as a format for presenting recent developments in each field, although such presentations will be one component of the Workshop. The principal feature of the Workshop will be small, intensive, interdisciplinary Discussion Groups that will examine progress in and current status of each of the aforementioned systems, and make specific recommendations for future directions. To our knowledge, there has never been a conference or workshop devoted specifically to an examination fof the mechanisms involved in CMC. Presentations related to CMC are always included as a subset of other immunological topics, and there certainly has never been any attempt to integrate information deriving from several different CMC systems. We also wish to avoid the standard short talk/poster session format to which CMC is usually relegated.